Whisk the egg yolks together in a heat-proof bowl. Set aside.

Heat the cream, milk, and sugar together in a heavy-bottomed saucepan.

Remove mixture just before boiling and slowly pour into the egg yolks whisking constantly.

Strain the mixture back into the saucepan.

Heat until it thickens, covering the back of a wooden spoon.

Pour back into the bowl, cover plastic wrap so the wrap is touching the mixture.

Refrigerate for 3 hours or overnight.

Pour the mixture into an ice cream maker.

Process according to the manufacturer's instructions.

When ice cream reaches soft serve consistency, stir in the blackberries.

Transfer to a freezer-proof container.

Place in the freezer for a few hours or until ready to serve.